Second draft of qfauto/qfisom, with qfisominit

[Bill Allombert <Bill.Allombert@math.u-bordeaux1.fr>]

Dear PARI developers,

following your suggestions at the Ateliers, I have created a new git branch
bill-qfisom-stage2 which adds two functions qfauto, qfisom and qfisominit

<http://pari.math.u-bordeaux1.fr/cgi-bin/gitweb.cgi?p=pari.git;a=shortlog;h=refs/heads/bill-qfisom-stage2>

This implements all AUTO/ISOM options except for the use of scalar product
combinations which is not finished yet.

The qfisominit() function allows to precompute data useful for subsequent call to
qfisom. This is useful if a form need to be compared to several others.

Cheers,
Bill.